1. Technical Field
The disclosure relates to a light-emitting diode (LED) driving circuit, and more particularly to a LED driving circuit which achieves a stabilized current output, over current protection, over voltage protection, and power factor correction.
2. Related Art
Current LED driving circuits can be generally divided into two types of isolated LED driving circuit and non-isolated LED driving circuit. The non-isolated driving circuit has three basic architectures, i.e., buck converter, boost converter, and buck-boost converter. No matter which architecture is used to drive the LED, an appropriate control circuit must be used in order to achieve a high power factor and a stabilized output current.
FIG. 1A shows a system diagram for a LED driving circuit according to the prior art. FIG. 1B is a block diagram for LED driving circuit according to the prior art. The architecture shown in FIG. 1A and FIG. 1B is a buck-boost converter. The buck-boost converter senses the phase signal of the input voltage, based on the sines table and digital control, the power factor correction (PFC) can be achieved. The buck-boost converter uses digital calculation to detect and control the current outputted to the LED, and thus the rapid over current protection can be achieved by analog control.
The above mentioned control method has functions of PFC and controlling the output current, but it is limited by the phase of the input voltage, the number of sample points for sines table, the response speed of the digital to analog converter (DAC) and etc. Therefore, the design complexity of the controller is increased.